Kristy S. Lane,1 B.A.; Maria E. St. Pierre,2 M.A.; Margo D. Lauterbach,1 M.D.; and Vassilis E. Koliatsos,1 M.D.

Patient Profiles of Criminal Behavior in the Context of Traumatic Brain Injury*

ABSTRACT: Traumatic brain injury (TBI) can lead to significant post-traumatic disturbances in mood and behavior, with the frontal lobes playing a key role in emotional and behavioral regulation. Injury to the frontal lobe can result in disinhibition and aggression which can result in police intervention and/or incarceration. We highlight four adult cases with a history of severe TBI with frontal lobe injuries and the presence of post-TBI criminal behaviors. There is evidence to support an anatomical basis for aggressive behaviors, yet there are other risk factors to be considered. Behaviors must be investigated thoroughly by obtaining adequate pre- and post-TBI psychiatric and psychosocial histories. By having a comprehensive understanding of aggression while appreciating the complex relationship between TBI, aggression, and premorbid risk factors, clinicians can more adequately treat patients with TBI, with the aim of potentially preventing criminal behaviors and recidivism.

KEYWORDS: forensic science, traumatic brain injury, frontal lobe, aggression, risk factors, recidivism, incarceration

Traumatic brain injury (TBI) is a significant public health concern and a leading cause of morbidity and mortality in the United States. TBI is defined as an alteration in brain physiology or anatomy caused by an external force

(1). Leading causes of TBI are falls (40.5%), motor vehicle collisions (14.3%), struck by/ against (15.5%), assault (10.7%), and unknown/other (19%)

(2). The severity of TBI can be determined, among else, with the Glas- Low Coma Scale (GCS), a 15-point scale measuring best motor, verbal, and eye-opening responses immediately after TBI. GCS scores are 13–15 for mild TBI, 9–12 for moderate, and 8 or below for severe. Clinicians may also utilize the Glasgow Outcome Scale (GOS) to measure recovery. Prognosis can vary based on key generic TBI variables (severity, type, and location of injury) as well as individual social, psychological, and general medical variables (prior psychiatric diagnoses, personality traits, available support systems, and physical limitations.) Aggression, acute or chronic, is a major complication of TBI.

There is no concrete definition of aggression in TBI research. One study’s definition of aggression is “verbal outbursts, physical violence toward objects, physical violence toward persons, and self-directed violence”

(3). The reported frequency of aggressive behaviors post-TBI ranges widely from 11% to 96%, suggesting a need for a concise definition of aggression

(4). The frontal lobe is involved in the suppression of aggressive

tendencies. Injury to the frontal lobe can cause impulsivity and

an inability to modify behavior, which can predispose one to aggressive and/or violent outbursts (5). Frontal dysfunction may also cause cognitive impairments in attention, memory, and planning. Individuals with frontal lobe injuries may also experience changes in personality, lack of awareness of deficits from injury (anosognosia), and anxiety or depression

(6). For the purpose of this report, we have adopted the definition of “aggression” as verbal outbursts and physical violence toward objects and others. In one study, authors recorded aggressive behaviors of 89

patients with a history of TBI and found an increased frequency of post-traumatic aggression among 33.7% of patients with TBI during the first 6 months after the trauma occurred (4). Individuals with frontal lobe lesions had a higher incidence of aggression as measured by the Overt Aggression Scale (OAS). In a recent longitudinal study, 35 of 135 participants (26%) were found to be aggressive between 6 and 60 months post-TBI

(7). Another study observed that verbal aggression was the most prevalent form of aggression; other subtypes included physical aggression against objects, self, and others. Among 67 first-time TBI patients, 28.4% reported verbal aggression, with the most common symptoms being angry shouts and vicious cursing with moderate threats of violence

(8). Aggressive behaviors cause serious social and often legal con-

sequences for the aggressor.